The present invention generally relates to a method and system for applying a coating, such as a substantially waterproof coating, to wood surfaces, especially to recessed and poorly accessible surface regions formed by checks, cracks, cuts, crevices, holes and the like.
Many wood objects, such as logs for log homes, utility poles, railroad ties, marine pilings, wooden bridge structures, and timber fences, are usually placed in outdoor environments in which the wooden objects are subjected to deteriorating forces such as sunlight, water, fungi and insects.
The foregoing types of wood objects are often surface-coated with weatherproofing paints, stains, and clear sealers, which often contain biocides (i.e., fungicides, algaecides and sometimes insecticides). Such coatings are most often applied conventionally by spraying or brushing, or, less frequently, by dipping the wooden object into a vat of liquid coating, which later hardens and develops its full physical properties. When such coatings are applied to the wood they usually or often perform their intended function and protect the coated wood from UV and visible radiation, water damage, and biological attack from fungi, algae and insects. However, wooden objects used outdoors often suffer from checks, cracks, holes and other similar features, with such crevices having recessed surfaces exposed to environmental effects (like, for example, collecting water) that frequently do not get coated when the rest of the object is surface-treated (via spray or brush) with a paint, stain, or clear sealer. Moreover, even when such wooden objects are initially dip-treated (and dip-treating does allow contact of a coating with all initially-existing recessed surfaces) they frequently develop checks and cracks at a later date (or have holes drilled into them by humans or eaten into them by insects) that then expose bare and vulnerable wood to the deteriorating effects of the environment.
In the log home industry, for example, several methods have been attempted to alleviate this problem. One method is to attempt spraying (with an airless sprayer or garden sprayer) a conventional coating into a check (usually the same coating used on the largely exposed and easily accessible exterior wooden surfaces of the log building) and coat the bare wood that comprises the inner sidewalls of the check. This approach has only limited effectiveness because many checks exist as a labyrinthine maze of contours and rough wood fibers and splinters that are difficult or impossible to coat directly with a spray, and often many such internal surfaces are left uncoated and unprotected.
Another approach used in the log home industry is to seal the larger checks (i.e., those about xe2x85x9cxe2x80x3 in width and larger) with elastomeric sealants, such as caulking or synthetic chinking, ideally preceded with round backer rod. Such caulking or chinking frequently suffers from failure because the inner lips of the check side walls are often poorly cleaned, or the sealant, when installed, is not well tooled, both of which problems can lead to adhesive failure of the sealant. Also, even when the sealant is well tooled and otherwise well installed, checks can continue to greatly open up over time, especially when xe2x80x9cgreenxe2x80x9d logs are used, which frequently results in excessive sealant stress and sealant failure.
Still another approach that has been occasionally and unsuccessfully tried in the log home industry is to apply foaming sealants (that retain a rigid and permanent foam structure as the sealant solidifiesxe2x80x94such as urethane foams). Such foam sealants are only well suited to applications within wall structures that are not exposed to exterior weather. When used where they are exposed to exterior weather, they typically deteriorate quickly, exhibit poor aesthetics, cannot handle the level of movement experienced by wood as it undergoes thermal and moisture cycling, and can actually trap moisture within the structure. Consequently, this approach is seldom, if ever, attempted any more.
The present invention generally relates to a method of applying a coating, such as a substantially water and weather proof coating, to recessed and poorly accessible wood surfaces using a collapsing foam coating material. The coating is initially sprayed into a recess in a wooden object (such as a check in a log on a log home), whereupon the coating immediately and vigorously foams up and forces the active ingredients of the coating (i.e., resins, water repellents, biocides, etc.) to come into complete and intimate contact with all the internal surfaces contained within the recess, with the foam subsequently collapsing in a relatively short period of time into a fluid that penetrates and seals all contacted wood surfaces. Because of the foaming action, the coating is forced into contact with, and seals all the surfaces of such hard to reach recesses in a way not possible with any other approach. Moreover, once the foam collapses and the coating becomes a thin liquid, the fluid flows by gravity into the most remote regions of the recess, puddles there, soaks in, and ultimately cures to offer the maximum possible protection to the wood where water is also most likely to flow, accumulate and otherwise cause damage.